FKIE_CVE-2026-56814
Vulnerability from fkie_nvd - Published: 2026-07-10 12:17 - Updated: 2026-09-24 22:17
Severity
Summary
Plug.Parsers.MULTIPART, the multipart request-body parser used to handle file uploads and multipart forms, does not enforce its :length budget against all consumed resources, allowing an unauthenticated remote attacker to cause denial of service. The parser charges the :length limit only for part body bytes; part header bytes are never counted, and a part with an empty body costs zero.
Because every part whose Content-Disposition carries a non-empty filename creates a fresh temporary file (via Plug.Upload) and retains a Plug.Upload struct for the duration of the request, an attacker can send a single request composed of many empty-body file parts. Such a request stays well under the configured :length limit (8,000,000 bytes by default) while creating one temporary file per part, leading to inode and disk exhaustion and unbounded memory growth. Any application using Plug.Parsers with the :multipart parser is affected, and no authentication is required, only reachability of a multipart endpoint over HTTP.
This vulnerability is associated with program files lib/plug/parsers/multipart.ex and program routines Plug.Parsers.MULTIPART.parse_multipart/2, Plug.Parsers.MULTIPART.parse_multipart_headers/5, Plug.Parsers.MULTIPART.parse_multipart_body/4, and Plug.Parsers.MULTIPART.parse_multipart_file/4.
This issue affects plug: from 1.4.0-rc.0 before 1.16.6, from 1.17.0 before 1.17.4, from 1.18.0 before 1.18.5, from 1.19.1 before 1.19.5, and from 1.20.0 before 1.20.3.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Plug.Parsers.MULTIPART\u0027"
],
"packageName": "plug",
"packageURL": "pkg:hex/plug",
"product": "plug",
"programFiles": [
"lib/plug/parsers/multipart.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Plug.Parsers.MULTIPART\u0027:parse_multipart/2"
},
{
"name": "\u0027Elixir.Plug.Parsers.MULTIPART\u0027:parse_multipart_headers/5"
},
{
"name": "\u0027Elixir.Plug.Parsers.MULTIPART\u0027:parse_multipart_body/4"
},
{
"name": "\u0027Elixir.Plug.Parsers.MULTIPART\u0027:parse_multipart_file/4"
}
],
"repo": "https://github.com/elixir-plug/plug",
"vendor": "elixir-plug",
"versions": [
{
"lessThan": "1.16.6",
"status": "affected",
"version": "1.4.0-rc.0",
"versionType": "semver"
},
{
"lessThan": "1.17.4",
"status": "affected",
"version": "1.17.0",
"versionType": "semver"
},
{
"lessThan": "1.18.5",
"status": "affected",
"version": "1.18.0",
"versionType": "semver"
},
{
"lessThan": "1.19.5",
"status": "affected",
"version": "1.19.1",
"versionType": "semver"
},
{
"lessThan": "1.20.3",
"status": "affected",
"version": "1.20.0",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Plug.Parsers.MULTIPART\u0027"
],
"packageName": "elixir-plug/plug",
"packageURL": "pkg:github/elixir-plug/plug",
"product": "plug",
"programFiles": [
"lib/plug/parsers/multipart.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Plug.Parsers.MULTIPART\u0027:parse_multipart/2"
},
{
"name": "\u0027Elixir.Plug.Parsers.MULTIPART\u0027:parse_multipart_headers/5"
},
{
"name": "\u0027Elixir.Plug.Parsers.MULTIPART\u0027:parse_multipart_body/4"
},
{
"name": "\u0027Elixir.Plug.Parsers.MULTIPART\u0027:parse_multipart_file/4"
}
],
"repo": "https://github.com/elixir-plug/plug",
"vendor": "elixir-plug",
"versions": [
{
"changes": [
{
"at": "981597d3a4271ede64373c7a731702a42c500dd6",
"status": "unaffected"
},
{
"at": "56edca2ce35fe5589cd581644d8a4493fa5f484e",
"status": "unaffected"
},
{
"at": "0ee8afcc61466dc5f7a8f048d0632c899165b81f",
"status": "unaffected"
},
{
"at": "cae36053350e5215a4e0ca33cd130af9c5fc6364",
"status": "unaffected"
},
{
"at": "f7effaed811c00b5f5bf817936bfd9c5df27b7dc",
"status": "unaffected"
},
{
"at": "df97d3f17f808a9916a7700a701fb85314559d56",
"status": "unaffected"
}
],
"lessThan": "*",
"status": "affected",
"version": "c52b2f32c90bccd718202bafccb5f95594e30183",
"versionType": "git"
}
]
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Plug.Parsers.MULTIPART, the multipart request-body parser used to handle file uploads and multipart forms, does not enforce its :length budget against all consumed resources, allowing an unauthenticated remote attacker to cause denial of service. The parser charges the :length limit only for part body bytes; part header bytes are never counted, and a part with an empty body costs zero.\n\nBecause every part whose Content-Disposition carries a non-empty filename creates a fresh temporary file (via Plug.Upload) and retains a Plug.Upload struct for the duration of the request, an attacker can send a single request composed of many empty-body file parts. Such a request stays well under the configured :length limit (8,000,000 bytes by default) while creating one temporary file per part, leading to inode and disk exhaustion and unbounded memory growth. Any application using Plug.Parsers with the :multipart parser is affected, and no authentication is required, only reachability of a multipart endpoint over HTTP.\n\nThis vulnerability is associated with program files lib/plug/parsers/multipart.ex and program routines Plug.Parsers.MULTIPART.parse_multipart/2, Plug.Parsers.MULTIPART.parse_multipart_headers/5, Plug.Parsers.MULTIPART.parse_multipart_body/4, and Plug.Parsers.MULTIPART.parse_multipart_file/4.\n\nThis issue affects plug: from 1.4.0-rc.0 before 1.16.6, from 1.17.0 before 1.17.4, from 1.18.0 before 1.18.5, from 1.19.1 before 1.19.5, and from 1.20.0 before 1.20.3."
}
],
"id": "CVE-2026-56814",
"lastModified": "2026-09-24T22:17:01.200",
"metrics": {
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-56814",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-10T14:03:11.744626Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-07-10T12:17:24.837",
"references": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://cna.erlef.org/cves/CVE-2026-56814.html"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/elixir-plug/plug/commit/0ee8afcc61466dc5f7a8f048d0632c899165b81f"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/elixir-plug/plug/commit/56edca2ce35fe5589cd581644d8a4493fa5f484e"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/elixir-plug/plug/commit/981597d3a4271ede64373c7a731702a42c500dd6"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/elixir-plug/plug/commit/c52b2f32c90bccd718202bafccb5f95594e30183"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/elixir-plug/plug/commit/cae36053350e5215a4e0ca33cd130af9c5fc6364"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/elixir-plug/plug/commit/df97d3f17f808a9916a7700a701fb85314559d56"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/elixir-plug/plug/commit/f7effaed811c00b5f5bf817936bfd9c5df27b7dc"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/elixir-plug/plug/security/advisories/GHSA-95qv-c9g9-rm63"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-56814"
}
],
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"vulnStatus": "Deferred",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-770"
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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